1. Field of the Invention
The present invention relates to a metal matrix composite casting in which particles, fibers, short fibers, whiskers or the like of, for example, ceramic are dispersed and a manufacturing method thereof.
2. Related Art
Metal matrix composites are materials formed by dispersing a property-improving materials such as particles and fibers in a metal serving as a host material. As one example of the metal matrix composites, there is an aluminum matrix composite in which ceramic particles are dispersed in aluminum. In a manufacturing process of the aluminum matrix composite, a preform of the ceramic particles is disposed in a casting metal mold and is incorporated within aluminum by die-casting.
The aluminum matrix composite is used, for example, as a part functioning as a heat-sink for a semiconductor power module. For a metal matrix composite functioning as a heat-sink, an aluminum-silicon carbide (Al-SiC) composite is generally used. Because of the necessity of mounting an IC substrate on the heat-sink, the heat-sink must be subject to a secondary process such as a surface finishing process and a hole forming process. However, since the Al-SiC composite is very hard, it is difficult to carry out the secondary process with respect to the Al-SiC composite, and therefore, the cost thereof becomes high.
In view of the problem discribed above, a method in which the surface of the Al-SiC composite is processed by utilizing an Al layer formed in the surface thereof at the time of manufacturing the Al-SiC composite has been proposed. U.S. Pat. No. 5,234,045, U.S. Pat. No. 5,570,502, U.S. Pat. No. 5,616,421)
In this method, however, since the formed Al layer is thin, the process of making the Al-SiC composite is difficult due to the influence of the underlying Al-SiC composite.